Influence of prenatal and postnatal lead exposure on discrimination learning in rats

The animals in this study were the offspring of dams, who, from 21-99 days of age, were exposed to 1000 mg/kg of lead acetate via a daily restricted watering schedule with exposure continuing throughout gestation and nursing. Control dams received distilled water under the same watering schedule. Offspring were weaned at 21 days of age and did not received lead treatment from that point. Testing began at 30 days of age with animals receiving 10 trials/day for 10 days on a brightness discrimination task conducted in a water-escape T-maze. This task was followed by a shape discrimination problem in the same apparatus. Analysis of results revealed that the lead-exposed pups made significantly more errors than the controls but had significantly shorter swimming times on both the brightness and shape discrimination tasks. The failure to attend to relevant discriminative cues may account for the observed deficits in lead-exposed animals.